Outboard motor noise isolation system

ABSTRACT

Disclosed herein is an outboard motor comprising a propulsion unit including a drive shaft housing rigidly connected to and supporting a power head, a gear case rigidly connected to the bottom of the housing, a shell extending in circular relation to the housing upwardly from the gear case, and resilient means including a wall extending between the housing and the shell adjacent to the bottom of the shell for locating the shell in spaced encircling relation to the housing and for enabling retention of water in the space above the wall and between the shell and the housing.

United States Patent Hait et al. Aug. '7, 1973 541 OUTBOARD MOTOR NOISE 1SOLAT10N 2,740,368 4/1956 lrgens et al. 115/18 SYSTEM 3,002,489 10/1961 Watkins 115/18 [75] Inventors: Gerald llatt, Brookfield; Theodore J.

Holtermann, Milwaukee, both of Wis.

[73] Assignee: Outboard Marine Corporation,

Waukegan, Ill.

[22] Filed: Apr. 7, 1971 [21] Appl. No.: 131,937

[52] US. Cl. 115/18, 60/310 [51] Int. Cl B63h 21/26 [58] Field of Search 115/17, 18; 181/39; 60/310, 272, 273

[56] References Cited UNITED STATES PATENTS 3,127,866 4/1964 Mohr 115/17 2,555,548 6/1951 Kiekhaefer....

3,198,162 8/1965 Larsen 3,358,668 12/1967 Post et al. 115/17 X Primary ExaminerMilton Buchler Assistant Examiner--E. R. Kazenske Attorney-Robert E. Clemency, John W. Michael, Gerrit D. Foster, Bayard H. Michael, Paul R. Puerner, Joseph A. Gemignani and Andrew 0. Riteris [57] ABSTRACT Disclosed herein is an outboard motor comprising a propulsion unit including a drive shaft housing rigidly connected to and supporting a power head, a gear case rigidly connected to the bottom of the housing, a shell extending in circular relation to the housing upwardly from the gear case, and resilient means including a wall extending between the housing and the shell adjacent to the bottom of the shell for locating the shell in spaced encircling relation to the housing and for enabling retention of water in the space above the wall and between the shell and the housing.

15 Claims, 3 Drawing Figures OUTBOARD MOTOR NOISE ISOLATION SYSTEM BACKGROUND OF THE INVENTION The invention relates generally to marine propulsion devices, such as outboard motors and stern drive units, and more particularly, to arrangements for effectively diminishing sound or noise propogation from such marine propulsion devices. Accordingly, the invention also relates to abatement or prevention of noise pollution by marine propulsion devices, such as outboard motors.

Among the principal sources of noise radiation from an outboard motor are the engine and drive shaft housing which supports the engine. Various prior solutions to the ever present problem of noise propagation reduction are disclosed in the following United States patents:

Irgens et al. US Pat. No. 2,740,368 issued Apr. 3, i956,

Watkins US. Pat. No. 3,002,489 issued Oct. 3, 1961,

Hulsebus US. Pat. No. 3,045,423 issued July 24, 1962,

Larsen US. Pat. No. 3,198,162 issued Aug. 3, 1965.

Attention is also directed to the US. Holtermann and Wick Patent application Ser. No. 855,292 filed Sept. 4, 1969.

SUMMARY OF THE INVENTION The invention provides a marine propulsion device comprising a marine propulsion unit including a drive shaft housing which is rigidly connected at its lower end to a gear case and a tubular shell which encloses the drive shaft housing and which is supported from the propulsion unit in spaced relation to the drive shaft housing by resilient means including a continuously annularly extending wall or seal connecting the lower part of the shell and the marine propulsion unit to thereby prevent the escape of noise from the space between the shell and the drive shaft housing and thereby also to afford retention of water in the space between the shell and the drive shaft housing.

The invention also contemplates arrangements for supplying water to the space orjacket between the shell and the drive shaft housing, for affording overflow and discharge of excess water, and for drainage of the jacket when the marine propulsion device is not in use. Marine propulsion devices constructed in accordance with the invention serve to divorce any noise or vibration occurring inside of the shell from the shell and to prevent transmission or propogation of such noises to the environment.

The invention also provides an outboard motor including a propulsion unit comprising a power head rigidly attached to the top of a drive shaft housing having a gear case rigidly attached to the drive shaft housing bottom, together with a shell in spaced surrounding relation to the drive shaft housing, and means extending from a king pin and directly resiliently connected, through suitable sealed apertures in the shell, to the drive shaft housing.

The invention also provides an outboard motor including a propulsion unit having a power head or engine rigidly mounted to the top ofa drive shaft housing, together with a shell which extends in generally continuously and encircling relation over and around the engine and the drive shaft housing and which is closed at the bottom by a seal which prevents the escape of noise from within the shell and facilitates retention of water in a jacket between the shell and the drive shaft housing.

The invention further provides an outboard motor including a shell which is resiliently mounted in spaced encircling relation to a drive shaft housing, together with a king pin which, at its bottom, is directly resiliently connected through, but independently of the shell, to the drive shaft housing, and which, at its upper end, is fixedly united to an engine shroud enclosing the sides and top of the engine or power head and connected, at its bottom, by a sound seal to the shell Also provided is a resilient connection between the power head and the shroud and thereby with the upper end of the king pin.

One of the principal objects of the invention is the provision of a marine propulsion unit, such as an outboard motor or stern drive unit, which operates at a noise level which is especially low to a close-by observer.

Another of the principal objects of the invention is the provision of a marine propulsion device including a drive shaft housing and means for reducing sound radiation from the drive shaft housing by encircling the drive shaft housing with a resiliently mounted sleeve which, together with the drive shaft housing and the resilient mounting arrangement, defines a water jacket around the drive shaft housing.

Another of the principal objects of the invention is the provision of an outboard motor having a propulsion unit which is directly resiliently mounted from the upper and lower ends of a king pin and which includes a shell or shroud encircling and covering the marine propulsion unit and closed at the bottom to prevent the escape of noise from within the shell and to facilitate retention of water in a jacket between the shell and a drive shaft housing.

Another of the principal objects of the invention is the provision of an outboard motor having a drive shaft housing which is encircled by a spaced tubular sleeve or shell and by provision of resilient means connecting the lower portion of the shell with the drive shaft housing to prevent the escape of noise from the space between the drive shaft housing and the shell and to facilitate retention of water in a jacket or space between the drive shaft housing and the shell.

Still another object of the invention is the provision of an outboard motor which can be economically manufactured and which will provide superior sound reduction characteristics over a long and useful life.

Other objects and advantages of the invention will become known by reference to the following description and accompanying drawings.

DRAWINGS FIG. I is a side elevational, schematic view, partially in section, of an outboard motor embodying various of the features of the invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a side elevational, schematic view, partially broken away and in section, of another outboard motor embodying various of the features of the invention.

GENERAL DESCRIPTION Shown in FIG. 1 is an outboard motor 11 embodying various of the features of the invention and including a propulsion unit 13 comprising an engine or power head 15 which is rigidly carried on the top of a lower unit 17 including a drive shaft housing 19 rigidly supporting the power head 15 and a gearcase 21 rigidly attached to the bottom of the drive shaft housing 19.

The drive shaft housing 19 internally supports a drive shaft 23 which is drivingly connected to the engine 15 and which is also drivingly connected to a propeller carrying shaft 25 through a reversing transmission 27.

The drive shaft housing 19 includes a hollow interior which can conventionally constitute a duct for exhaust gases discharged from the engine or power head 15. In turn, the gearcase 21 can conventionally include passages communicating with the interior of the drive shaft housing 19 for affording underwater exhaust gas discharge either through the hub of a propeller 29 or through a fin 31.

Also incorporated in the outboard motor shown in FIG. 1 is a transom or clamp bracket 33 which is adapted to be mounted on a boat and which supports a horizontally extending pintle 35 which, in turn, supports a swivel bracket 37. In turn, the swivel bracket 37 rotatabl y carries a king pin 39 which is disposed in generally perpendicular relation to the pintle 35 and which is connected to the drive shaft housing 19 to afford steering movement of the propulsion unit 13 relative to a boat. As thus far described, the construction is generally conventional.

In accordance with the invention and in order to reduce sound radiation from the side walls of the drive shaft housing 19, an outer shell or tube 41 is resiliently mounted from the propulsion unit 13 in encircling relation to the drive shaft housing 19 and is arranged to retain ajacket of water around the drive shaft housing 19. In addition, the shell 41 can integrally include an engine enclosing shroud part (See FIG. 3) or a separate engine enclosing shroud 43 can be supported in enclosing relation to the engine 15.

More particularly as shown in FIG. 1, the shell 41 is a tubular member which extends, except as otherwise explained, in generally unbroken and spaced relation to the drive shaft housing 19 and is mounted to the propulsion unit 13 by resilient means. Although such means can take various forms, in the disclosed construction, such means includes mounting of the lower end of the shell 41 by a lower annular resilient member or ring 45 which serves to isolate and space the shell 41 from the propulsion unit 13, to constitute the bottom wall of a water jacket 47 between the drive shaft housing 19 and the outer shell 41 and to prevent escape of noise from space between the outer shell 41 and the drive shaft housing 19.

As shown, the shell 41 extends upwardly from the gearcase 21 with the annular resilient member 45 intervening between the shell 41 and the gearcase 21. The shell 41 and gearcase 21 are designed to provide an over-all smooth configuration to the outer surface of the outboard motor 11.

The resilient means which mounts the shell 41 from the propulsion unit 13 also includes one or more resilient elements in spaced relation above the lower resilient wall or ring 45 for properly locating and spacing the shell 41 relative to the propulsion unit 13. Thus, in the construction shown in FIG. 1, an upper annular resilient ring 49 is provided between the shell 41 and the propulsion unit 13 adjacent to the top of the drive shaft housing 19. Use of annular members for mounting the shell 41 from the propulsion unit 13 has the advantages of avoiding complicated arrangements for connecting or locating spaced discrete resilient elements.

Means are provided for resiliently isolating and supporting the drive shaft housing 19 from the king pin 39. While other arrangements can be employed, in the disclosed construction, as shown in FIG. 2, the lower end of the king pin 39 is fixed to a bifurcated bracket 51 having spaced legs 53 extending rearwardly in straddling relation to the shell 41 and drive shaft housing 19. In addition, the drive shaft housing 19 is provided, on the opposite sides thereof, with oppositely extending bosses 5S. Extending from the central portion of the outer ends of the bosses 55 are projections 57 which extend through enlarged apertures 59 in the sides of the tubular shell 41. Captured between the inside surface of the margin of the shell 41 around the apertures 59 and the annular surfaces at and around the base of the projections 57 at the outer ends of the bosses 55, as well as between the walls defining the apertures 59 and the cylindrical peripheries of the projections 57, are respective resilient seals 61 which afford resilient spacing of the outer shell 41 from the drive shaft housing 19 and retention of the watertight integrity of the water jacket 47 between the outer shell 41 and the drive shaft housing 19. i

The projections 57 extending from the bosses 55 0n the drive shaft housing 19 are connected to the bracket legs 53 by respective isolatorsor rubber mounts 63. Thus, the lower king pin bracket 51 is connected through openings or apertures 59 in the shell and by suitable rubber mounts 63 directly to the drive shaft housing 19 while, at the same time, there is provided additional resilient support for the shell 41 and the watertight integrity of the water jacket between the shell 41 and the drive shaft housing 19 is maintained.

While other arrangements could be employed, in the construction shown in FIG. 1, noise radiation from the engine or power head 15 is reduced by enclosing the power head 15 in the shroud 43 which is rigidly fixed to the upper end of the king pin 39 and therefor can be regarded as unitary with the king pin 39. In order to complete support of the propulsion unit 13 from the king pin 39, the upper part of the engine or power head 15 includes a boss or pad 65 supporting an isolator or rubber mount 67 which is also connected to an arm 69 fixedly extending from the shroud 43. Thus, the propulsion unit 13 is supported from the king pin 39 in general accordance with the disclosure of the Holtermann and Wick application Ser. No. 855,292 filed Sept. 4, 1969.

At its upper end, the shroud 43 includes a removable cover 71 and, at its lower end, the shroud 43 is open and extends in partially overlying relation to the upper part of the shell 41. In order to prevent escape of noise through the opening between the shell 41 and the lower end of the shroud 43, an annular continuously extending sound seal 73 of resilient material is employed.

Also in accordance with the invention, water is supplied to the water jacket 47 between the shell 41 and the drive shaft housing 19. Various arrangements can be employed. Specifically, a portion of the water discharged by a conventional water pump 78 can be supplied directly to the water jacket 47. Alternatively, discharge water from an engine cooling jacket 75 can be supplied through a passage 77 to the water jacket 47.

In accordance with the invention, means are also provided for discharging excess water from the jacket. While various arrangements can be employed, in the disclosed construction, such means can include an overflow aperture 79 in the shell 41, whereby to afford immediate overboard discharge and to avoid dumping water into the interior of the drive shaft housing 19. Alternatively, the drive shaft housing 19 can be provided with an overflow aperture 81 which determines the level of water in the jacket 47 and which allows excess water to be conventionally dumped into the interior of the drive shaft housing 19 for underwater discharge with the exhaust gas.

It is also preferable to provide the water jacket 47 with a restricted drain or bleed hole (not shown) located adjacent to the bottom of the water jacket to afford drainage when the outboard motor is removed from the water. Such a bleed hole can be either in the shell 41, whereby to drain overboard, or in the drive shaft housing 19, whereby to afford drainage through the exhaust gas passages. The flow capacity of the aperture or hole is sufficiently restricted so as to require a considerable length of time to drain the water jacket 47.

Still further, the water jacket 47 could comprise a portion of an engine cooling water supply line from the pump 78 to the engine water jacket 75 or a portion of a return line from the engine water jacket to the pump 78 in the case of an engine having a recirculating cooling system. As already indicated, the size of the drain hole would be materially restricted so as not to adversely interfere with the over-all system for supplying the engine with cooling water.

Shown in FIG. 3 is another embodiment of an outboard motor 111 including various of the features of the invention. As in the embodiment of FIG. 1, the outboard motor 111 of FIG. 3 includes a propulsion unit 113 comprising a power head 115 arrangement rigidly attached to the top of a drive shaft housing 119 which also has rigidly connected to the bottom thereof a gearcase 121.

The outboard motor shown in FIG. 3 also includes a clamp bracket 133 which is adapted to be connected to the transom of a boat and which supports a horizontal pintle 135 connected to a swivel bracket 137 to afford vertical tilting movement of the swivel bracket 137 relative to the boat. The swivel bracket 137 pivotally carries a king pin 139 which extends in transverse relation to the pintle 135 and is fixed to upper and lower U-shaped brackets 151 which are constructed in a manner similar to the bracket 51 and which have legs 153 connected through resilient isolators or mounts 163 to the drive shaft housing 119 in the same general manner as has been explained with respect to FIGS. 1 and 2.

As in the embodiment disclosed in FIG. 1, in order to reduce noise radiation from the drive shaft housing 119 there is provided a tubular shell 141 which is resiliently mounted in spaced encircling relation to the drive shaft housing 119 and which extends upwardly from slightly above the waterline under normal speed operation. In order to reduce sound radiation from the engine, the shell 41 includes an integrally extending shroud part 143 which encloses the engine 115.

As in the embodiment shown in FIG. 1, in order to resiliently mount the shell 141 from the propulsion unit 113 and to simultaneously space the shell 141 from contact with the propulsion unit 113 and to provide a bottom wall for the space between the shell 141 and the propulsion unit 113, thereby to prevent the escape of sound waves traveling within the shell and, at the same time, to afford retention of water in the space between the shell and the propulsion unit, there is provided adjacent the bottom of the shell, a lower annular resilient sound sealing member or ring 145 extending between the shell 141 and the drive shaft housing 119.

As in the embodiment shown in FIG. 1, there is also provided, adjacent the upper end of the drive shaft housing 119, an upper annular resilient member or ring 173 which supports and spaces the shell 141 from the propulsion unit 113.

In the embodiment shown in FIG. 2, the propulsion unit 113 is directly mounted from the king pin 139 and, at the same time, the shell 141 is spaced and supported, by connecting the king pin 139 thorugh the upper and lower brackets 151 to the drive shaft housing 119 in the manner illustrated in FIG. 2 and previously explained in connection therewith.

As in the embodiment shown in FIG. 1, water can be supplied to, and discharged and drained from the water jacket 147 in the manner already explained with respect to the embodiment of FIG. 1. a

The disclosed constructions effectively contain the sound generated and radiated by the engine and the drive shaft housing by enclosing the engine and drive shaft housing in an enclosing shell and by sealing the shell around the propulsion unit so as not only to prevent radiation of sound but so as to prevent escape of sound waves traveling in the space between the shell and shroud andthe propulsion unit. In addition, the addition of the water in the jacket around the drive shaft housing serves to materially reduce sound transmission to the environment.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. An outboard motor comprising a propulsion unit including a power head, and a housing rigidly connected to and depending from said power head, a tubular shell, means resiliently mounting said shell from said propulsion unit in outwardly spaced encircling relation to said housing and including a resilient wall extending between said housing and said shell adjacent to the bottom of said shell to enable retention of water in the space above said wall and between said shell and said housing and to prevent the escape of noise from the space between said shell and said housing, a first bracket adapted to be connected to a boat, a second bracket adapted to be connected to said first bracket about an axis approximately horizontal when said first bracket is connected to a boat, a king pin pivotally extending in said second bracket about a second axis transverse to said first mentioned axis and forwardly of said housing, and means extending through an opening in said shell and directly connecting the lower end of said king pin to said housing to afford steering movement of said propulsion unit about said second axis, said connecting means including resilient mounts.

2. An outboard motor in accordance with claim 1 wherein said housing includes a hollow interior portion constituting an exhaust gas duct, and further including a drive shaft extending through said housing and wherein said propulsion unit further includes a gearcase rigidly connected to said housing at the bottom 6. An outboard motor'iri acear'aaaaaiv'rirreriiair wherein said shroud includes a removable cover portion.

7. An outboard motor in accordance with claim 1 ineluding ,shmii F QQEEM s my?! head n wherein said king pin is fixedly connected, at its upper end, to said power head shroud.

8. An outboard motor in accordance with claim 7 wherein said shroud extends rigidly from said shell.

9. An outboard motor in accordance with claim 7 wherein said shroud is resiliently connected to said shell.

10. An outboard motor in accordance with claim I wherein said shell includes an upper part in enclosing relation to said power head.

11. An outboard motor in accordance with claim 10 wherein said enclosing part includes a removable cover.

12. An outboard motor in accordance with claim it) wherein said king pin is fixedly connected at its upper end to said upper part of said shell.

13. An outboard motor in accord ance with claim 1 including means for supplying water to the space between said shell and said housing and restricted means for draining water from the space between said housing Sa hill; a a 7..

14. An outboard motor in accordance with claim 1 including means for overflowing excess water from the space between said shell and said housing.

15. A marine propulsion device comprising a propulsion unit including a drive shaft housing, and a gearcase rigidly connected to the bottom of said drive shaft housing, a tubular shell, and means resiliently mounting said shell from said propulsion unit in outwardly spaced encircling relation to said drive shaft housing and with said shell extending upwardly from adjacent to said gearcase, and including a resilient wall extending between said housing and said shell adjacent to the bottom of said shell to enable retention of water in the space above said wall and between said shell and said housing, a king pin located forwardly of said housing, and means extending through an opening in said shell for directly connecting said king pin to said housing and including resilient mounts.

l I i 

1. An outboard motor comprising a propulsion unit including a power head, and a housing rigidly connected to and depending from said power head, a tubular shell, means resiliently mounting said shell from said propulsion unit in outwardly spaced encircling relation to said housing and including a resilient wall extending between said housing and said shell adjacent to the bottom of said shell to enable retention of water in the space above said wall and between said shell and said housing and to prevent the escape of noise from the space between said shell and said housing, a first bracket adapted to be connected to a boat, a second bracket adapted to be connected to said first bracket about an axis approximately horizontal when said first bracket is connected to a boat, a king pin pivotally extending in said second bracket about a second axis transverse to said first mentioned axis and forwardly of said housing, and means extending through an opening in said shell and directly connecting the lower end of said king pin to said housing to afford steering movement of said propulsion unit about said second axis, said connecting means including resilient mounts.
 2. An outboard motor in accordance with claim 1 wherein said housing includes a hollow interior portion constituting an exhaust gas duct, and further including a drive shaft extending through said housing and wherein said propulsion unit further includes a gearcase rigidly connected to said housing at the bottom thereof and including shafting connected to said drive shaft and exhaust gas discharge means communicating with said housing hollow interior portion.
 3. An outboard motor in accordance with claim 1 wherein said resilient mounting means further includes an additional resilient element located above said wall and between said shell and said propulsion unit.
 4. An outboard motor in accordance with claim 1 and further including a shroud enclosing said power head and resiliently connected to said shell.
 5. An outboard motor in accordance with claim 4 including a resilient connection between said shroud and said power head.
 6. An outboard motor in accordance with claim 4 wherein said shroud includes a removable cover portion.
 7. An outboard motor in accordance with claim 1 including a shroud enclosing said power head and wherein said king pin is fixedly connected, at its upper end, to said power head shroud.
 8. An outboard motor in accordance with claim 7 wherein said shroud extends rigidly from said shell.
 9. An outboard motor in accordance with claim 7 wherein said shroud is resiliently connected to said shell.
 10. An outboard motor in accordance with claim 1 wherein said shell includes an upper part in enclosing relation to said power head.
 11. An outboard motor in accordance with claim 10 wherein said enclosing part includes a removable cover.
 12. An outboard motor in accordance with claim 10 wherein said king pin is fixedly connected at its upper end to said upper part of said shell.
 13. An outboard motor in accordance with claim 1 including means for supplying water to the space between said shell and said housing and restricted means for draining water from the space between said housing and said shell.
 14. An outboard motor in accordance with claim 1 including means for overflowing excess water from the space between said shell and said housing.
 15. A marine propulsion device comprising a propulsion unit including a drive shaft housing, and a gearcase rigidly connected to the bottom of said drive shaft housing, a tubular shell, and means resiliently mounting said shell from said propulsion unit in outwardly spaced encircling relation to said drive shaft housing and with said shell extending upwardly from adjacent to said gearcase, and including a resilient wall extending between said housing and said shell adjacent to the bottom of said shell to enable retention of water in the space above Said wall and between said shell and said housing, a king pin located forwardly of said housing, and means extending through an opening in said shell for directly connecting said king pin to said housing and including resilient mounts. 